1. Field of the Invention
This invention relates generally to self-aligning bearings and particularly concerns a retaining clip for accurately mounting a ball or roller bearing upon a plastic carrier of a clutch release bearing assembly.
2. Description of Prior Developments
Self-aligning clutch release bearings are generally mounted upon a carrier or sleeve which slides over a shaft or quill during engagement and disengagement of an operatively associated clutch member. One approach to mounting the bearing to the carrier has involved deforming or rolling over an axial end portion of a cylindrical metal carrier member to form an annular radial flange which serves to axially restrain the bearings on the carrier. This approach has presented several drawbacks.
First, the rolling of deformation of the carrier generally limits the selection of carrier materials to metals. Recent developments have suggested the desirability using plastic materials for forming the carrier, including increased dimensional accuracy, reduced weight and reduced cost.
Second, the rolling of the end of the carrier to form a retaining flange is difficult to accurately control and has been associated with serious operational problems during bearing use. For example, bearing preload is often controlled by the axial pressure generated by a preload element such as a belleville, cone or annular wave spring which is compressed between the radially deformed carrier flange and an axial end surface of a bearing race. Since the bearing preload is quite sensitive to the degree of axial compression of the preload element, minor deviations in the axial location of the carrier flange due to uncontrollable axial tolerances produced during formation of the flange produce large variations in bearing preload thereby leading to unsatisfactory bearing performance.
Still another problem associated with the formation of a bearing retaining flange by rolling or swaging a radial flange on a metal bearing carrier is the axial and radial dislocation of the preload spring from its intended operational position between the flange and bearing. As the flange is formed, it may cause the preload spring to shift to distort in such a manner that uniform contact between the bearing and washer is lost. This causes an uneven circumferential loading on the bearing which further adversely affects bearing performance.
Yet another drawback to a rolled or swaged flange is the difficulty experienced in checking the finished bearing assembly during quality control operations. Once the flange is formed by a rolling operation there is no known method to quickly and easily check the finished part for bearing preload accuracy. That is, the amount of deformation of the carrier flange during rolling varies considerably in practice and is not easily measured.
Finally, the rolling or swaging process is relatively time consuming and generally cumbersome since all parts must be held together for a considerable period of time while the flange is slowly deformed. If the rolling operation is carried out too quickly, the metal being deformed will tear thereby resulting in a defective part which must be scrapped.
Accordingly, a need exists for an improved mounting assembly for accurately locating a bearing and preload element both axially and radially on a plastic carrier so as to closely control bearing preload, improve bearing performance and facilitate assembly and quality control operations.